This invention relates to an electric stringed musical instrument and, more particularly, to a pickup incorporated in the electric stringed musical instrument for converting vibrations of the string to an electric signal.
Acoustic stringed musical instruments each have resonators. The violin, viola, cello and double-bass are categorized in the violin family, and the resonators are formed inside the bodies. While a musician is bowing a piece of music on the acoustic stringed musical instrument, the bow gives rise to vibrations in the strings for generating tones. The vibrations are propagated through a bridge to the resonator, and are magnified through the resonator. The vibrations in turn are propagated from the resonator to the air as the tones. Thus, the resonators are indispensable components of the acoustic stringed musical instruments.
On the other hand, the vibrations are electrically magnified in the electric stringed musical instruments. Several electric stringed musical instruments are, by way of example, sized like the members of the violin family, and are corresponding to the violin, viola, cello and double-bass. The electric stringed musical instrument corresponding to the violin is hereinbelow referred to as xe2x80x9celectric violinxe2x80x9d. While a musician is playing a tune on the electric violin, the strings are bowed, and the bow gives rise to vibrations as similar to the acoustic stringed musical instrument as similar to the acoustic violin. However, the vibrations are converted to an electric signal, and the electric signals are amplified through a suitable amplifier for generating loud electric tones.
A pickup is provided for converting the vibrations to the electric signal. The pickup unit is implemented by a single piezoelectric element, which is provided under the bridge. The vibrations are provided from the four strings to the bridge, and the bridge exerts fluctuating pressure on the piezoelectric element. The piezoelectric element converts the fluctuating pressure to the electric signal. Thus, only one piezoelectric element is shared between the four strings.
The fundamental frequency in the four strings is varied in dependence on the tones to be generated. On the other hand, the piezoelectric element has own frequency characteristics. This means that the piezoelectric element can not evenly respond to the vibrations in all the strings. As a result, the electric tones are liable to be unbalanced.
A solution is proposed in U.S. Pat. No. 4,867,027 to Barbera. The U.S. Patent teaches a resonant pick-up system, which is incorporated in an electric stringed instrument. The prior art resonant pick-up system includes a transducer cartridge assembly upright on a body of the stringed instrument. The transducer cartridge assembly includes a cartridge body, which has an upper portion or crown portion and a lower portion or base portion. The crown portion is vibratory, but the base portion is non-vibratory. Slots and cavities are formed in the crown portion. The slots radially downward extend from the upper edge of the crown portion, and separate the crown portion into xe2x80x9cvibrating supporting crown sections or segmentsxe2x80x9d. The cavities are formed in the vicinity of the bottom ends of the slots, and are radially elongated from the base portion into the segments. The segments are formed with shallow receiving grooves, and the shallow receiving grooves are open at the crown edges of the segments. The shallow receiving grooves are aligned with the center axes of the slots, respectively. The strings pass the shallow receiving grooves, and are held in contact with the upper surfaces of the segments.
In one embodiment disclosed in the U.S. Patent, piezoelectric elements are mounted within the cavities. Bimorph piezoelectric transducers are recommended in the U.S. Patent. Barbera describes the piezoelectric elements, xe2x80x9cThus, the piezo-elements are mounted along the longitudinal axis of its respective cavity so that one end is fixed to the vibrating portion of section and the other end is fixed to the lower non-vibrating stationary base portion.xe2x80x9d
Barbera further discloses another embodiment in the U.S. Patent for the cello or base. U-shaped recesses are formed in the cartridge base support. The U-shaped recesses make the upper portion of the cartridge base support into plural sections, which are merged into the rigid lower portion of the cartridge base support. Piezo-electric cartridges are provided in the U-shaped recesses. The piezo-electric cartridges are secured at the lower portions thereof to the walls defining the lower portions of the U-shaped recesses. As a result, each of the cartridge assemblies xe2x80x9cprovides a singular flexible upper portion above the notch which will vibrate freely with respect to the mass of the bridge and be free of interaction or interference with any of the other cartridgesxe2x80x9d. A cavity is formed in the piezoelectric cartridge below the notch, and a piezoelectric element is located therein.
A problem is encountered in the prior art electric stringed musical instrument in that the electric signals, which are output from the piezoelectric elements, are too small in magnitude. This results in that pieces of music information are liable to be inaccurately transferred from the vibrations to the electric signals. As a result, the electric tones become different from the tones intended by the musician.
It is therefore an important object of the present invention to provide a pickup unit, which converts vibrations to electric signals at good fidelity.
The present inventor contemplated the problem inherent in the prior art resonant pickup system, and noticed that the vibrations were indirectly propagated from the strings to the piezoelectric elements through the segments, which were merged into the non-vibratory base portion or lower portion. This meant that the flexural rigidity was increased from the crown edges toward the non-vibratory base portion. Even though the vibrations were propagated from the strings to the crown edges of the segments, the vibrations were gradually decayed toward the non-vibratory base portion or lower portion, and, accordingly, only part of the vibration energy was propagated to the piezoelectric elements or piezoelectric cartridges. The present invention concluded that vibration mediators such as the vibratory segments were to be physically separated from any non-vibratory portion.
In accordance with one aspect of the present invention, there is provided a pickup unit for a stringed musical instrument comprising a stationary member attached to a body of the stringed musical instrument and having plural zones, plural transducers connected at certain portions thereof to the stationary member in the plural zones, respectively, and deformable in response to repeated forces respectively exerted thereon in certain directions for producing electric signals representative of the forces, and plural vibration mediators connected between strings of the stringed musical instrument and other portions of the plural transducers for transmitting the repeated forces from the strings to the plural transducers and having a freedom to move in at least the certain direction in the plural zones, respectively.